As a method for treating an organic waste, there is known a method for treating a waste using a steam at a high temperature and a high pressure in a sealed vessel, for example (refer to Patent Document 1, for example). It is considered that the conventional method for treating a waste using the steam hardly generates toxic nitrogen oxides, sulfur oxides, and the like, which are generated in a treatment by incineration, thus there pose no problems of environmental pollution, and a safe waste treatment can thus be expected.    [Patent Document 1]    Japanese Patent Publication No. 2000-33355